The present invention relates to an apparatus for gas/liquid separation and more particularly to such as apparatus comprising a housing surrounding at least one normally vertically extending tubular wall defining a substantially tubular inner space and a substantially annular outer space within the housing. The housing has an inlet means for supplying a mixture of a liquid and gas into said inner space and an outlet means for separately discharging the liquid and the gas from the inner space. A swirl imparting means is disposed inside the inner space for imparting a rotary movement to the mixture of liquid and gas to separate the liquid and the gas.
The term gas is taken throughout the specification and the claims to also include vapor.
Devices of the above mentioned type are widely used in the oil and chemical industry. They may be applied in columns for merely separating gas/liquid mixtures, as well as in columns for contacting liquids and gases for generating an exchange of matter and/or heat between the phases and subsequently separating the phases. The above devices are normally mounted in or over openings in one or more horizontal trays. If the above mentioned devices are applied in columns for contacting liquids and gases, they are provided with mixing chambers having separate liquid and gas inlet means. In said mixing chambers the liquid is atomized in the supplied gas stream so that matter and/or heat between the liquid and gas may be exchanged. The so formed mixture of liquid and gas is supplied to the swirl imparting means of said devices for subsequently separating the liquid from the gas stream.
An example of an apparatus of the above type is described in British Pat. No. 1,123,546. This known apparatus comprises a cylindrical wall enclosing an inner space, in which a vane assembly is arranged for separating liquid from a gas/liquid mixture. The cylindrical wall is provided with liquid discharge openings for the withdrawal of the major part of the separated liquid. During operation a minor part of the separated liquid will leave the inner space via the upper end of the cylindrical wall.
Another example of a device of the above type for gas/liquid separation is described in U.S. Pat. No. 4,015,960. This known apparatus comprises an inner space enclosed by a tube and provided with blades for imparting a rotary movement to a mixture of liquid and gas introduced into said inner space via the open lower end of the tube. The liquid, being separated from the gas stream upon passing said blades, can be discharged from the inner space via an opening in the wall of the tube. The liquid discharge opening is arranged on approximately the same level as the blades. The remaining gas stream can be discharged from the inner space via an outlet tube arranged coaxially with the main tube and having the lower end thereof arranged inside said main tube.
The above mentioned known devices have a satisfactory separating action at rather moderate flow velocities of the mixtures to be treated and at rather moderate liquid loads. Both an increase of the flow velocity and an increase of the liquid load will, however, cause a decrease of the separating efficiency. This efficiency reduction is caused by the phenomenon of re-entrainment of liquid by the gas stream on leaving the inner space of the treating apparatus.
U.S. Pat. No. 4,349,360 describes an improved version of the type of devices known from the above mentioned publications. This improved gas/liquid treating apparatus is provided with a gas outlet, indicated with the expression primary gas outlet means, having its lower end arranged below the upper end of the inner space and separate secondary gas outlet means for withdrawing gas from the liquid flow leaving the inner space. The arrangement of the primary and secondary gas outlets enables a better separation of gas and liquid at higher loads.